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'\" t
.\" Title: uuidd
.\" Author: [see the "AUTHOR(S)" section]
.\" Generator: Asciidoctor 2.0.20
.\" Date: 2025-02-26
.\" Manual: System Administration
.\" Source: util-linux 2.41
.\" Language: English
.\"
.TH "UUIDD" "8" "2025-02-26" "util\-linux 2.41" "System Administration"
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.SH "NAME"
uuidd \- UUID generation daemon
.SH "SYNOPSIS"
.sp
\fBuuidd\fP [options]
.SH "DESCRIPTION"
.sp
The \fBuuidd\fP daemon is used by the UUID library to generate universally unique identifiers (UUIDs), especially time\-based UUIDs, in a secure and guaranteed\-unique fashion, even in the face of large numbers of threads running on different CPUs trying to grab UUIDs.
.SH "OPTIONS"
.sp
\fB\-C\fP, \fB\-\-cont\-clock\fP[\fB=\fP\fItime\fP]
.RS 4
Activate continuous clock handling for time based UUIDs. \fBuuidd\fP could use all possible clock values, beginning with the daemon\(cqs start time. The optional argument can be used to set a value for the max_clock_offset. This guarantees, that a clock value of a UUID will always be within the range of the max_clock_offset.
.sp
The option \fB\-C\fP or \fB\-\-cont\-clock\fP enables the feature with a default max_clock_offset of 2 hours.
.sp
The option \fB\-C<NUM>[hd]\fP or \fB\-\-cont\-clock=<NUM>[hd]\fP enables the feature with a max_clock_offset of NUM seconds. In case of an appended h or d, the NUM value is read in hours or days. The minimum value is 60 seconds, the maximum value is 365 days.
.RE
.sp
\fB\-d\fP, \fB\-\-debug\fP
.RS 4
Run \fBuuidd\fP in debugging mode. This prevents \fBuuidd\fP from running as a daemon.
.RE
.sp
\fB\-F\fP, \fB\-\-no\-fork\fP
.RS 4
Do not daemonize using a double\-fork.
.RE
.sp
\fB\-k\fP, \fB\-\-kill\fP
.RS 4
If currently a uuidd daemon is running, kill it.
.RE
.sp
\fB\-n\fP, \fB\-\-uuids\fP \fInumber\fP
.RS 4
When issuing a test request to a running \fBuuidd\fP, request a bulk response of \fInumber\fP UUIDs.
.RE
.sp
\fB\-P\fP, \fB\-\-no\-pid\fP
.RS 4
Do not create a pid file.
.RE
.sp
\fB\-p\fP, \fB\-\-pid\fP \fIpath\fP
.RS 4
Specify the pathname where the pid file should be written. By default, the pid file is written to \fI{runstatedir}/uuidd/uuidd.pid\fP.
.RE
.sp
\fB\-q\fP, \fB\-\-quiet\fP
.RS 4
Suppress some failure messages.
.RE
.sp
\fB\-r\fP, \fB\-\-random\fP
.RS 4
Test uuidd by trying to connect to a running uuidd daemon and request it to return a random\-based UUID.
.RE
.sp
\fB\-S\fP, \fB\-\-socket\-activation\fP
.RS 4
Do not create a socket but instead expect it to be provided by the calling process. This implies \fB\-\-no\-fork\fP and \fB\-\-no\-pid\fP. This option is intended to be used only with \fBsystemd\fP(1). It needs to be enabled with a configure option.
.RE
.sp
\fB\-s\fP, \fB\-\-socket\fP \fIpath\fP
.RS 4
Make uuidd use this pathname for the unix\-domain socket. By default, the pathname used is \fI{runstatedir}/uuidd/request\fP. This option is primarily for debugging purposes, since the pathname is hard\-coded in the \fBlibuuid\fP library.
.RE
.sp
\fB\-T\fP, \fB\-\-timeout\fP \fInumber\fP
.RS 4
Make \fBuuidd\fP exit after \fInumber\fP seconds of inactivity.
.RE
.sp
\fB\-t\fP, \fB\-\-time\fP
.RS 4
Test \fBuuidd\fP by trying to connect to a running uuidd daemon and request it to return a time\-based UUID.
.RE
.sp
\fB\-h\fP, \fB\-\-help\fP
.RS 4
Display help text and exit.
.RE
.sp
\fB\-V\fP, \fB\-\-version\fP
.RS 4
Display version and exit.
.RE
.SH "EXAMPLE"
.sp
Start up a daemon, print 42 random keys, and then stop the daemon:
.sp
.if n .RS 4
.nf
.fam C
uuidd \-p /tmp/uuidd.pid \-s /tmp/uuidd.socket
uuidd \-d \-r \-n 42 \-s /tmp/uuidd.socket
uuidd \-d \-k \-s /tmp/uuidd.socket
.fam
.fi
.if n .RE
.SH "AUTHOR"
.sp
The \fBuuidd\fP daemon was written by \c
.MTO "tytso\(atmit.edu" "Theodore Ts\(cqo" "."
.SH "SEE ALSO"
.sp
\fBuuid\fP(3),
\fBuuidgen\fP(1)
.SH "REPORTING BUGS"
.sp
For bug reports, use the \c
.URL "https://github.com/util\-linux/util\-linux/issues" "issue tracker" "."
.SH "AVAILABILITY"
.sp
The \fBuuidd\fP command is part of the util\-linux package which can be downloaded from \c
.URL "https://www.kernel.org/pub/linux/utils/util\-linux/" "Linux Kernel Archive" "."
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